package targetToOffer.ninthDay;

/**
 * @author Godc
 * @description
 */
public class Exist {
    public static void main(String[] args) {
        ExistSolution s = new ExistSolution();
        char[][] strings = {{'A', 'B', 'C', 'E'}, {'S', 'F', 'C', 'S'},{'A','D','E','E'}};
        boolean abcced = s.exist(strings, "ABCCED");
        System.out.println(abcced);
    }
}
class ExistSolution {
    public boolean exist(char[][] board, String word) {
        char[] words = word.toCharArray();
        for(int i = 0; i < board.length; i++) {
            for(int j = 0; j < board[0].length; j++) {
                if(dfs(board, words, i, j, 0)) return true;
            }
        }
        return false;
    }
    boolean dfs(char[][] board, char[] word, int i, int j, int k) {
        if(i >= board.length || i < 0 || j >= board[0].length || j < 0 || board[i][j] != word[k]) return false;
        if(k == word.length - 1) return true;
        // 防止回头探索
        board[i][j] = '*';
        boolean res = dfs(board, word, i + 1, j, k + 1) || dfs(board, word, i - 1, j, k + 1) ||
                dfs(board, word, i, j + 1, k + 1) || dfs(board, word, i , j - 1, k + 1);
        board[i][j] = word[k];
        return res;
    }

}